Magneto



July 4, 1944. K. A. HARMoN ET AL MAGNETO Filed June 26 1942 4 Sheets-Sheet l m@ N5 ww v wh,

July 4, 1944. K. A. HARMON ET Al.

MAGNET@ Filed June 26, 1942 4 Sheets-Sheet 2 July 4, 1944. K, A. HARMON ET AL 2,352,894

MAGNETO Filed June 26, 1942 4 Sheets-Sheet 3 HHHHHUIII` I July 4, 1944' K. A. HARMON ET Al. 2,352,894

MAGNETO Filed June 26, 1942 4 Sheets-Sheet 4 237% I 1&9

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' ATTO NEYs Puentes Julya, 1944 MAGNlrro Kenneth A. Hamon and Sidney x. smart, Long-- meadow, Mass., assi to Wlco Electric Company, West Springiield, Mass., a corpora-l tion of Massachusetts Application .Tune ze, mz, serial No. 448,536

(ci. 11i-zoe) 12 claims.

This invention relates to magnetos and, more particularly. to magnetos which are especially suited for use in furnishing ignition for aircraft engines.

'I'he invention has for an object the provision of an improved amature structure, involving two coil cores and two coil units thereon for providing dual ignition, and a single magnetic rotor for controlling flow of flux through both cores and coil units, characterized in'that the cores radiate from the axis of rotation of the rotorl and in that the coils on the cores are located one on each side of said axis.

The invention also has for an object to provide a magneto for dual ignition having a pair of armature units, a pair of breaker units, and a pair of distributor units, and drive shaft means extending between the units of each of said pairs, said uneanshaving thereon a single magnetic rotor for controlling flux flow through both armature units, a single cam for actuating both breaker units and a single rotor for actuating both distributors.

Another object of the invention is to provide in a magneto of the type described, an improved arrangement and disposition of the various nunc-conducting elements of the magnetic circuits, characterized in that said elements may be grouped within a housing in compact relation around the drive shaft of the magneto.

These objects will best be understood as the detailed description proceeds and they will be pointed out in the appended claims.

The invention will be disclosed with reference to the accompanying drawings, in which:

Fig. l is a sectional elevational view of a magneto embodying the invention;

Figs. 2, 3, 4, and 6 are cross sectional views taken on the lines 2 2, 3 3, 4 4, 5 5 and 5 6, respectively, of Fig. l;

Fig. '1 is a fragmentary sectional elevational view taken on the line 1 1 of Fig. 5;

Fig. 8 is a fragmentary sectional view taken on the line 8 8 of Fig. 4;

Figs. 9 and 10 are fragmentary sectional views taken on the lines 9 9 and III-I0 respectively, of Fig. 3; and

Fig. l1 is a diagrammatical view showing the electrical connections of the magneto.

Referring to these drawings and particularly to Fig. 1 thereof, the magneto includes a housing which is made up of any suitable non-magnetic material and which comprises a central and; tubular body portion I5 and two covers or end walls I8 and I1 for closing opposite ends of the portion I5. The covers I8 and I1 are secured to the body I5 by cap screws I3 and I9, respectively. The coils, magnetic rotor and all elements of the magnetic circuits of the magneto, together with the breaker mechanisms, are containedwithin the body portion. The distributors are contained within the cover IB which is cup-shaped for that purpose. The other cover or end plate I1 serves in part to support the drive shaft of the magneto and to support the housing from the engine with which the magneto is used. For this purpose the plate I1 has a pilot 20 to fit a hole in the engine crankcase and a flange 2I which is adapted to be bolted to said crankcase.

The tubular casing I5 has an outer portion 22 (Fig. 4) which is of circular cross section and an inner portion 23 which is of the irregular cross sectional shape shown in Fig. 2 and of less width than 'the portion 22. At the intersection of these portions 22 and 23 are flat faces 24 which lie in a plane at right angles to the axis of the portion 22 (see also Fig. 8). Located centrally in the portion 23 (Figs. 1 and 2) is a hollow hub 25, the lower end of which flares outwardly into a part 26 oi' larger diameter. This hub is an integral part of casing section I5 and is connected thereto near its outer end by spider arms 21 (Fig. 3). The inner end of casing I5 (Fig. 1) is turned inwardly toward the hub 25 and terminates with a circular flange I5 to receive a corresponding flange on the end section l1. The inner end of casing section IIS therefore has an annular slot 28 between the outer periphery of hub 25 and the inner periphery of iiange I5'. There is also the central hole 29 through hub 25 but otherwise the inner end of section I5 is closed.

The magnetic rotor enters through the slot 28. It includes a plurality (six in this case) of short bar magnets 30 (Fig. 2), mounted in angularlyspaced relation in a circular series coaxial with .the hub 25. Each magnet has pole shoes 3| made up of iron laminations suitably held together, as by rivets 32. The magnets and shoes are assembled on top of a face plate 33 of non-magnetic material and moved into the iproper radial positions against a form, after which wedge blocks 34 of non-magnetic lmaterial are driven in, one between each pair of pole shoes, to hold the parts in place. While the wedge blocks are held in the positions shown, a ring 35 of non-metallic material is laid on top of the magnets, shoes and.

wedge blocks and a hole is drilled through each block and the ring and face plate to receive a tapered pin 36. 'I'he ends of each pin 36 after being driven home. are headed over, one against the i'aceiplate and one against a washer 31, which lies against ring 35. The pole shoes 3| are provided with outer convex pole faces 35 and inner concave pole faces ll. These faces are coaxial with the hub 25.

The magnetic rotor is driven by a shaft I5 to which the hub of face plate 23 is splined as indicated in Fig. I. 'I'his shaft is supported in part in hub 25 and in part in the end plate I1. An outer ball bearing II is set into a counterbore in the outermost end face of hub 25 and an inner ball bearing I2 is mounted in the hub of cover I1. These bearings II and 42 rotatably support the shaft, as indicated. The inner race of the inner bearing l2 is mounted on the hub of face plate 32 and abuts a shoulder on such hub. The face plate abuts a flange 43 on shaft 40. A sleeve Il, also splined to shaft 40, carries a gear 45 to mesh with a driving gear (not shown) in the engine crankcase. A nut 45, threaded on the inner end of shaft l0, serves to force the sleeve against the inner race ofbearlng l2 and the latter against the shoulder on the hub of face plate 33 and the latter against flange I3, thereby holding the sleeve, inner race and face plate in proper axial position on the shaft. A suitable seal 41 cooperates with a part of sleeve 44 as shown in Fig. 1. Theouter end of shaft III receives breaker cam 4B which is splined thereto and also clamped in axial position between a nut Il and the inner race of the outer bearing 4I.

The amature structure of the magneto will next be described. There are two circularand coaxial series of pole pieces for cooperation with the pole shoes 3| of the rotor. One series, the inner one, consists ofv a plurality (six as shown) of pole pieces 50 angularly spaced about the hub 25. Each pole piece 50 has a convex pole face 5I which is coaxial with the hub and shaft Il and which is adapted for cooperation with the concave faces 39 of the pole shoes 3| of the rotor. The other and outer series consists of a plurality (six as shown) of pole pieces 52, which are angularly spaced about the shaft and hub and which have concave pole faces 53 coaxial therewith. The pole faces 53 are adapted for cooperation with the convex pole faces of the pole shoes 3| of the rotor.

Beyond the rotor is a laminated member (Figs. l and 3) which extends diametrically across the casing I5 in parallel relation to the face plate of the rotor. This member affords two coil cores 5l, one on each side of hub 25, and a central ring 5l which interconnects the inner ends ofthe two cores. These three parts are integral. The ring '5l is formed by dividing the laminations at the center, spreading them apart and bending them into the form shown.

The inner series of pole pieces are connected to the ring 55. This is en'ected by a plurality of flux-conducting members 55 (Figs. 2 and 8), one for each pole piece 50 as herein shown. Each pole piece 5I) and its flux-conducting member 53 are integral and they are made up of laminations of the shape shown in Fig. 8. These laminations are suitably bound together into a unit. as by the rivets 51, and the units are fixed in the hub section 25 and its enlargement 25, in any suitable way, as by embedding them in the non-magnetic metal of the casing I5 during the casting thereof. The members 56 parallel the shaft and extend up to the level of the fiat faces 2l, terminating with finished end @faces on which the ring 55 rests. On each core 54 is mounted a coil case 53 of instacca sulating material which case contains a primary coil 55 and a secondary coil 6U.

The pole pieces 52 of the outer series (Fig. 2) are divided into two groups of three each. The units of each group are interconnected by an arcshaped laminated member BI which extends part way around the section 23 of casing I5 in a plane at right angles to the axis of shaft 40 and is suitably fixed to the casing. Each member BI has connected thereto a flux-conducting member 52 which extends parallel to the axis of shaft 4l (Fig. l) along an outer wall of the casing and terminates with a finished end face in the same plane as the end faces of the inner members 5I. The outer ends of the cores 54 rest one on each of these finished end faces of the outer flux-conducting members 62. The cores 54 and the ring 55, from which they radiate, may be held to the several end faces described in any suitable way, as for example by the clips 83 (Fig. 3), one engaging each outer end of each of the cores 5l. These clips may be secured by cap screws il one theraded into each of the fiat faces 24.

The pole pieces 52 and their arc-shaped connecting member 5I are integral. They are made up of a stack of laminations and secured together in any suitable way, as by the rivets 65. Alternate members of each stack have extensions which are bent up at right angles to the member 5I and form the outer flux-conducting member 52. The laminations of each member 52 are suitably held together in group form, as by the rivets 56. The laminated unit 52, 5I, 52 is fixed to the outer wall of casing section 23 in any suitable way. As herein shown. the two end pole pieces 52 of each member 6I are surrounded (above, below, in back and on the outer end) by the non-magnetic metal of which the casing I5 is cast. Thus, as will be clear from Fig. 2, each arc-shaped member 6I is held against inward or outward radial movement and turning movement. Also, as will be clear from Fis. v10, it is likewise held from movement parallel to 'the axis of shaft 40. Each member 6I is therefore securely anchored to the housing. The outer iiux-conducting members 62 lie in recesses 61 in the wall of housing section 23 and there is clearance between the sides of these members and the sides of the recesses. The back of each member 62 engages the bottom of the recess but elsewhere the member is out of contact with the metal of the casing. The purpose of this arrangement is to avoid an eddy current loss which would otherwise occur if the member 62 were surrounded by a metal loop. For a similar reason the clips 53 do not engage but two walls of the coresll. Each member 82 is anchored to the housing near its upper end (Fig. l) by embedding the special head 58 of the rivet .66 in the metal of housing I5. This head is surrounded by such metal and holds its member 62 against the bottom of its groove 61.

Two breaker mechanisms are provided. Both are supported from a bridge 59 (Figs. 4 and 8) which spans diametrically across the casing section 22 at right angles to and beyond the cores 5I. This bridge has legs 10, one at each end thereof, with out-turned feet 1I which abut one on each of the faces 24 and are secured thereto by cap screws 12. 'I'he legs 10 also have finished pilot portions 13 (Fig. 8) which engage the iinished curved surface 1I of the section 23. The two breaker mechanisms on the bridge are located one on each side of the cam 48. 'I'he two breaker mechanisms are alike lo that a description of` one will sumce for both. `Each such mechanism is mounted on a plate 18. These plates are located between a hub 18. upstanding centrally from the bridge, andflanges 11 upstanding one from each end of the bridge. The ends of each plate 15, as well as thesurfaces of the hub 18 and flanges 11 which they engage, are finished surfaces coaxial with shaft 48. Each plate is held in place by two screws 18 which pass through curved slots in the plate coaxial with the shaft, and serve to clamp the plate to the bridge in various positions of angular adjustment relatively to the shaft. An eccentric 19, `iournaled in the bridge 88, lies in a recess in plate 18 and serves when turned. to move the plate around the axis of shaft 48 when screws 18 are loosened.

The plate closely fits between the hub 18 and flange 11 is guided to swing about the shaft as a center. The plate\15 has xed thereto the pivot stud 88 for the breaker arm 8|, which carries the movable breaker point 82. The stationary breaker point 83 is xed to a lug on a plate 84 which lies on top of plate 15 and is pivoted on stud 88. Two screws 85 serve to clamp plate 84 to plate 15 and these screws pass through1 also serves to move the breaker arm against cam 49.

A condenser 89 is provided for each breaker. Each condenser is mounted in a metal, car'- tridge-like casing 98 (Figs. 3 and 8). One terminal of the condenser is the casing itself and the other terminal 9| is insulated from the casing. 'I'he casing 98 is supported by a metal plate 82. Each plate is clamped against an insulating block 94 on one of the faces 24 by one of a pair of cap screws 93, which thread into lugs 98 upstandingfrom the face 24. Thus, the plates 92 and the condensers 89 are grounded. One end of each condenser casing 98 is received in a small well 98 formed in one of the faces 24. Each block 9,4' (Fig. 9) carries a condu-cting plate 91, xed thereto by screws 98. Each plate 91 has a projecting end which is engaged by the contact spring 99 of a member |88 electrically connected to a wire |8| which connects With the usual grounding switch indicated in Fig. 11 at The electrical connections of the primary oircuit will be clear from Fig. 11. One terminal of each primary coil 59 is grounded. The other terminal is connected by a wire |83 to the insulated terminal 88 and thus to the breaker arm 8| andl movable breaker point 82. The breaker point 83 is grounded. A wire |84 connects the terminal 88 to the insulated terminal 9| of the condenser 89 and a wire |88 connects the terminal 9| to plate 91 and thus to the grounding switch |82. The secondary coils 88 eachhave one terminal grounded. The other terminal of one secondary coil is connected by a conductor |88 to the rotatable electrode |81 of a distributor which successively moves into lposition so thatA the high tension sparks can jump to the distributor contacts |88. These contacts are connected one to each of a series of twelve plugs some of which are indicated at |89. The second distributor has similar contacts H8 and a rotatable electrode |I| which is connected by a conductor I2 to one terminal of the other secondary coil. The other terminal of the latter is grounded. The contacts ||8 are connected, one to each of a second series of twelve spark plugs, some of which are indicated at H3. The electrodes |81 and simultaneously come into position opposite two contacts |88 and H8, respectively, and the two spark plugs |89 and H8 which are respectively connected to said contacts are positioned in the same cylinder of the engine.

The distributors, diagrammatically indicated in Fig. 11, are constructed as shown in Figs. 1, 5 and 7. Referring to Fig. l, the distributors are combined and both are housed within the cover |8. There is an inner stator block ||1 which is common to both distributors and made of suitable insulating material. In this block v||1 are molded outer and inner metallic feed rings ||8 and H9, having a plurality (twelve in this case) of outwardly projecting contacts |28 and |2I, respectively. The conductors |88 and ,||2, previously described, are integral parts of the rings ||8 and ||9 respectively, and they ex-,- tend inwardly and radially outwardly into position to be engaged by the ungrounded terminals |22 of secondary coils 88. These terminals are mounted one in each of two hollow hubs |22, which project radially one from each of the coil housings 88 and are adapted to enter hollow hubs |24 formed on the base of block I1.v The block I |1 has four feet |25 (Fig. 5) which support it from the section 22 of the housing. The

section 22 is indented at four angularly-spaced points as shown in Fig. 3, to form supports |28 and these feet |25 rest one on each of these supports as indicated in Fig. 5. Fig. 7 clearly shows one of these feet in place on its support. Cap screws |21 fasten these feet to the supports as indicated.

'I'he distributors .are provided with an outer stator block |28 of insulating material (Figs. 1 and 5). This block is suitably secured to cover I8, as by the rivets |29, and like the cover, is roughly cup-shaped and telescopes the inner stator block ||1. The block |28 supports the two sets of output contacts |88 and ||8, arranged, respectively, in the planes of feed rings ||9 and |I8. A skirt-like barrier |29' on block |28 extends suiiciently beyond the contacts |88 to prevent flash-over from these contacts to the mey in the base of sockets |3| formed in the hub |82 of the block. The twelve sockets |3| are arranged in an inner circular series as shown in Fig. 6. Surrounding this series is an outer and coaxial circular series of sockets |33. The contacts 8 are integral parts of wires |34 which are molded in block |28 (Fig. 1) and extend to and terminate in the base of sockets |33. The sockets 3| and |33 receive the spark plug Wires |38 and |38 leading to the spark plug |89 and I I3, respectively.

'I'hese wires |38 and |38 enter through a metallic conduit, exemplified in part by the fitting |31 which is secured by screws |38 to and closes theopening in the end of cover I8. The wires pass through openings in a circular gland plate |38 and through openings in a rubber ring |48- the latter having tubular parts |4| one to enter each of the sockets III and |83 and having also a flange |42 to telescope hub |82. The gland plate |88 is forced inwardly when screws |88 are tightened, thereby compressing the rubber ring |48 and forcing it into close contact with each spark plug wire and into close contact with the inner wall of cover I8, thus sealing off the distributor chamber from the conduit |81.

The rotor of the distributor is rotatably supported from the stator block |28. A stud |48 is clamped to a metal insert |48' in block |28 as indicated in Fig. 1. This stud supports the inner races of two ball bearings |44 which races are separated by a spacer sleeve |45. A nut |46 clamps the inner races and spacer sleeve |45 in position as indicated. The outer races of these bearings are fixed one in each end of a tubular metal insert |41 molded into the body 48 of the rotor. For driving the rotor, the insert |41 is provided with an extension |49 which is directed axially inward to engage in a notch in an extension |50 of the cam 48 (see also Fig. 8). The rotor body which is of insulating material, has its hub telescoped in the central hole in the inner stator block I1. The rotor body extends outwardly in opposite directions from its hub (Fig. and inwardly into the annular space between the two stator blocks ||1 and |28 (Fig. l). On one side, the rotor extends inwardly to, or slightly beyond, the plane of feed ring ||8 and carries the electrode I to successively connect the feed ring contacts |20 with one or another of the contacts ||0. On the other side, the rotor extends inwardly a greater distance and carries an electrode |01 for successively connecting the feed ring contacts |2| with one or another ci the contacts |08.

The operation of the magneto will next be described. Referring to Fig. 2, the magnetic rotor, turning in the direction of the arrow, will make and break a magnetic circuit through each coil core twelve times per revolution. The rotor is shown in one of its twelve sparking positions in Fig. 2. Two circuits, in each of which the flux travels axially outward through the members 58, radially outward through the coil cores 54 and axially inward through the members 62, have just been broken and circuits in the reverse dircction have been established. A reversal of flux through both primary coils 59 thus occurs simultaneously. At the moment when the rotor moves into the illustrated position, the twelve-lobed breaker cam 48 simultaneously separates both sets of breaker points 82 and 83 and thus opens both primary circuits. The E. M. F. simultaneously induced in each secondary coil 80 results in two sparks which occur simultaneously in the same cylinder of the enginethe electrodes |01 and being then positioned as shown in Fig. 5 so as to cooperate respectively, with one of the contacts |08 and with one of the contacts ||0.

As the rotor continues to turn in the illustrated direction the shoes 3| of north polarity move into full engagement with the pole pieces 52 and the shoes 8| of south polarity move into full engagement with the pole pieces 50. The breaker cam 48 then allows the breaker points to close. The primary circuits are thus closed and the eiect of the closed-circuit primary coils is to resist change of flux in the magnetic circuits. Just before the shoes 8| of north polarity leave the pole pieces 52 and before the shoes 3| of south polarity leave the pole pieces 50, succeeding pole shoes of south polarity have engaged pole pieces 52 and succeeding pole shoes of north polarity have engaged pole pieces to set up a magnetic circuit in the reverse direction. Then, when the first described circuit is broken sumciently and the breaker points again open. a quick reversal of iiux will occur simultaneously in both coil cores and high tension sparks will be produced in two more spark plugs, both located in another cylinder of the engine. This condition occurs when the rotor has moved 30 degrees from the illustrated position. A succeeding 30 degree movement of the rotor will similarly cause another reversal of ilux in the coil cores and the production of two more sparks in another cylinder of the engine and so on-ilux changes and resulting sparks being produced at each 30 degree movement of the rotor.

The tubular portion of the housing is machined from opposite ends. First, working from the inner end, said portion is bored out up to the level of the faces 24 to the finished diameter of the faces 53 of the pole pieces 52 of the outer series and it is also bored out to a less depth sufficient to finish the faces 5| of the inner pole pieces. Also, the inner end face of flange I5' is faced off. The remaining machining operations are performed from the outer end of said tubular portion. The outer end faces of the fluxconducting members 62, the outer end face of hub 25, including the embedded members 58, the feet |26 and the faces 24 may all be finished with an end mill, working from said outer end. Then, the rotor and driving shaft are put in place through the inner end of said tubular portion, after which the inner end closure I1 is bolted in place. The coil units are slipped on their cores 54 on opposite sides of the ring 55 and this laminated member 54, 55 is put in place and secured by the clips 88 and screws 64, working from the outer end of the tubular -portion of the housing. The bridge 88, having the two breaker mechanisms assembled thereon, is put in place through said outer end and secured by screws 12. The breaker cam 48 is then assembled on shaft 40; the condenser casings 90 put in place, together with the ground terminals; and al1 the wiring for the primary circuits is done. The inner stator block Ill is then ,put in place with its feed |25 resting on supports |28 and the screws |21 are applied to fasten the feet and supports together. Then the outer stator block |28 and the distributor rotor |48 are assembled in the order named in cover I8, after which this cover is applied to close the outer end of the tubular portion of the housing and is fastened thereto by the screws I8.

The invention affords an improved arrangement of the flux-conducting elements of the armature of the magneto. These elements are packed within the tubular casing and around the drive shaft in exceedingly compact relation. The greatest radial dimension of this casing, measlured from the axis of the shaft, is but slightly greater than the minimum permissible radial dimension of the distributor. The arrangement enables the two coil units and cores therefor, necessary for a dual magneto, to be mounted within the small space limits shown and served by a single magnetic rotor. Likewise the. two breaker units are served by a single cam 48 and the two distributors are served by a single rotor |48. The invention nevertheless affords a very eii'ilcient magneto for furnishing dual ignition for airplane engines having a large number of cylinders.

What we claim is:

1. In a magneto. a magnetic rotor. a drive shaft therefor, a plurality of generating coils, cores one for each coil, said cores radiating from the shaft with their axes located at right angles to the axis thereof, and inner and outer flux-conducting members extending respectively from the inner and outer ends of the cores in a direction along the shaft and into position for cooperation with said rotor.

2. In a. magneto, a magnetic rotor, a drive shaft therefor, a plurality of generating coils, cores one for each coil, means interconnecting the inner ends of said cores, said cores radiating from said shaft with their axes located at right angles to the axis thereof, and inner and outer flux-conducting members extending respectively from the said interconnecting means and from the outer ends of said cores in a direction along the shaft and into position for cooperation with said rotor.

3. In a magneto, a magnetic rotor, a drive shaft therefor, a plurality of generating coils, cores one for each coil, said cores radiating from the shaft with their axes located at right angles to the axis thereof, inner and outer fluxconducting members extending respectively from the inner and outer ends of the cores in adirection along the shaft and into position for cooperation with said rotor; and a housing of nonmagnetic material for enclosing said coilscores, members and rotor; said housing having a tubular portion with a central hub supported therein, said inner and outer members being fixed respectively in said hub and in said tubular portion.

4. In a magneto, a magnetic rotor, a drive shaft therefor, a plurality of generating coils, cores one for each coil, said cores radiating from the shaft with their axes loca-ted at right angles to the axis thereof, inner and outer flux-conducting members extending respectively from the inner and outer ends of the cores in a direction along the shaft and into position for cooperation with said rotor; and a housing of nonmagnetic material for enclosing said coils, cores, members and rotor; said housing having a tubular portion with a central hub supported therein, said inner and outer members being fixed respectively in said hub and in said tubular portion, said cores being separable from said inner and outer members.

5. In a magneto, a magnetic rotor, a drive shaft therefor, a plurality of generating coils, cores one for each coil, said cores radiating from the shaft with their axes located at right angles to the axis thereof, inner and outer flux-conducting members extending respectively from the inner and outer ends of the cores in a direction along the shaft and into position for cooperation with said rotor, and a housing of nonmagnetic material for enclosing said coils, cores, members and rotor, said housing having a tubular portion with a central hub supported therein4 and having removable end walls for closing opposite ends of said tubular portion, said inner and outer members being fixed respectively in said hub and in said tubular portion, said cores being separable from said inner and outer members and removable therefrom and replaceable thereon through one of said end walls, said rotor being removable and replaceable through the other of said end walls.

6. In a magneto, a magnetic rotor, a drive shaft therefor, a plurality o f generating coils, cores one for each coil, said cores radiating from the shaft with their axes located at right angles to the axis thereof, inner and outer flux-conducting members extending from the inner and outer ends of the cores in a direction along the shaft and into position for cooperation with said rotor, a housing of non-magnetic material for enclosing said coils, cores, members and rotor, said housing having a, tubular portion with a central hub supported therein and having removable end walls for closing opposite ends of said tubular portion, said inner and outer members being fixed respectively in the hub and tubular portion, said cores being separable from said limer and outer members and removable therefrom and replaceable thereon through one of said end walls, said rotor being removable and replaceable through the other of said end walls, and bearings for said shaft one in said last-named end wall and one in said hub. y

7. In a magneto, a magnetic rotor, a driving shaft therefor, said rotor having a plurality of bar magnets angularly-spaced in a circular series around the axis of rotation of said shaft. pole shoes for said magnets, each shoe having an inner concave and anouter convex face in coaxial relation with said shaft, an inner and an outer circular series of angularly-spaced pole pieces having convex and concave faces coaxial with said shaft for cooperation respectively with the concave and convex faces of said shoes, a

plurality of cores radiating from said axis andspaced axially away from the pole shoes of said rotor, generating coils one on each core, fluxconducting means interconnecting the inner ends of said cores and extending along said axis to and connecting with all the pole pieces of said inner series, and flux-conducting means interconnecting all the pole pieces of said outer series and extending spbstantially parallel with the first-named means to and connecting with the outer ends of said cores.

8. In a magneto, a housing of non-magnetic material having a tubular portion, a removable end Wall closing one end of said portion, a removf able member closing the other end of said portion, a hollow hub located centrally in said portion and supported from the wall thereof by radially-extending connecting means, a drive shaft rotatably mounted in said end wall and -hub and extending through said wall and through and beyond said hub, an inner circular series of pole pieces coaxial with said shaft and xed in said hub, an outer circular series of pole pieces coaxial with said shaft and fixed in the wall of said tubular portion, a magnetic rotor fixed to said shaft and having a, circular series of magnets and pole shoes therefor to cooperate with said pole pieces, a plurality of inner and a pair of outer flux-conducting members extending respectively from the inner and outer series of pole pieces in a direction along the shaft and terminating with end faces, said pair of members being located at opposite points in said tubular portion, a laminated member spanning said portion at right angles to said means and interconnecting the end faces of said pair of outer members and connected with the end faces of the inner,memberscoil units each comprising primary and secondary coils arranged on said laminated member one on each side of said shaft, a bridge removably secured to said tubular portion and spanning the same at right angles to the laminated member, said bridge and said connecting means located on opposite sides of the laminated member, a pair of breaker mechanisms mounted at opposite points on said bridge, said shaft extending through and beyond said bridge, and a cam fixed to said shaft for actuating both breaker m.

9. In a magneto, a housing of non-magnetic material having a tubular portion, a removable end wall closing one end of said portion, a cupshaped removable member closing the other endA` of said portion, a hollow hub located centrally in said portion and supported from the wall thereof by a radially-extending connecting means. a drive shaft rotatably mounted in said end wall and hub and extending through said wall and through and beyond said hub, an inner circular series of pole pieces coaxial with said shaft and fixed in said hub, an outer circular series of pole pieces coaxial with said shaft and ilxed in the wall of said tubular portion, a magnetic rotor fixed to said shaft and having a circular series of magnets and pole shoes therefor to cooperate with said pole pieces, a plurality of inner and a pair of outer flux-conducting members extending respectively from the inner and outer series of pole pieces in a direction along the shaft and terminating with end faces, said pair of members being located at opposite points in said tubular portion, a liminated member spanning said portion at right angles to said connecting means and interconnecting the end faces of said pair of outer members and connected with the end faces of said inner members, coil units each comprising primary and secondary coils arranged on said laminated member one on each side of said convex pole faces coaxial with the shaft for cooperation respectively with the convex and concave pole faces of the pole pieces of the inner and outer series.

11. In a magneto, a housing of non-magnetic material having a tubular portion, a pair of removable end walls closing opposite ends of said portion and a central hollow hub supported from the tubular portion and having its ends spaced one from each of the adjacent end walls; a drive shaft extending through said hub and through one end wall and supported in part by the hub and in part by the last-named end wall, a magnetic rotor fixed to the drive shaft between the last-named end wall and the adjacent end of said hub, said rotor having a plurality of bar magnets angularly-spaced in a circular series around said shaft and having pole shoes for the magnets, each said shoe having inner concave and outer convex pole faces coaxial with said shaft, an inner and an outer circular series of angularly-spaced pole pieces having convex and concave pole faces coaxial with said shaft for respective cooperation with the concave and convex pole faces of said pole shoes, a plurality of inner flux-conducting members connected at one 1 end to said inner pole pieces and embedded in shaft, a bridge removably secured to said tubular portion and spanning the same at right angles to the laminated member, said bridge and said connecting means being located on opposite sides of the laminated member, a pair of breaker mechanisms mounted at opposite points on said bridge, said shaft extending through and beyond said bridge, a single cam iixed to said shaft for actuating both breaker mechanisms, a pair of distributors mounted in the cup-shaped member, and a single rotor for actuating both distributors drivingly connected to said shaft.

, 10. In a magneto, a magnetic rotor, a driving shaft therefor, an inner circular series of pole pieces singularly-spaced around said shaft and having convex pole faces coaxial therewith, a plurality of inner nuit-conducting members each connected at one end to one of said pole pieces and extending alongside said shaft and terminating at the other end with a finished end face, an outer circular series of pole pieces angularlyspaced around said shaft and having concave pole faces coaxial therewith, outeriiux-conducting members one on each side of said shaft and one connected to some of the outer pole pieces and the other connected to the rest of the outer pole pieces, said outer members extending substantially parallel to the inner members and each terminating with a finished end face, and a laminated member having its ends engaged one with each of the finished end faces of said outer members and having its laminations spread apart at a location between its ends and bent to form a ring, said ring encompassing said shaft and engaged with the finished end faces of said inner members, said laminated member affording a pair of cores one on each side of said ring, said rotor having a plurality of bar magnets angularly-spaced in a circular series around said shaft, and having poles shoes for the magnets, each said shoe having inner concave and outer said hub and extending along the same to the opposite end thereof, a laminated flux-conducting member having a central ring and two diametrically-opposed cores radiating therefrom and spanning the tubular portion of said casing, said ring engaging the opposite ends of the inner flux-conducting members, outer flux-conducting members embedded in said tubular portion and connecting the outer ends of said cores to the pole pieces of the outer series, means for fastening said laminated member in said casing, and generating coils one on each core.

12. In a magneto. a housing of non-magnetic material having a tubular portion with a central hollow hub supported therefrom and removable end walls for closing opposite ends of said portion, a pair of laminated flux-conducting members anchored to the wall of said tubular portion one on each side of said hub in opposed relation, each said member comprising an arc-shaped portion extending part way around the inner wall of the tubular portion parallel to a plane at right angles to the axis of said hub and provided with a plurality of angularly-spaced pole faces coaxial with said hub and a portion at right. angles to the arc-shaped portion, said second-named portion extending along the inner wall of the tubular portion in a direction substantially parallel to the axis of said hub and terminating with a finished end face, a plurality of angularly-spaced fluxconducting members anchored to said hub and having on one end a plurality of angularlyspaced pole faces coaxial with said hub, and at the other end terminating with a finished end face, a iiux conducting member having its outer ends engaged one with each of the flrst-named finished end faces and intermediate its ends being engaged with the second-named end faces, generating coils on the last-named member one on each side of said hub, and a magnetic rotor cooperating with said pole faces to make and break magnetic circuits through said flux-conducting members and coils.

KENNETH' A. HARMON. SIDNEY K. SMART. 

